Once versus twice daily low molecular weight heparin for the initial treatment of venous thromboembolism

BACKGROUND: In the initial treatment of venous thromboembolism (VTE) low molecular weight heparin (LMWH) is administered once or twice daily. A once daily treatment regimen is more convenient for the patient and may optimise home treatment. However, it is not clear whether a once daily treatment regimen is as safe and effective as a twice daily treatment regimen. This is the second update of a review first published in 2003. OBJECTIVES: To compare the efficacy and safety of once daily versus twice daily administration of LMWH. SEARCH METHODS: For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 2013) and CENTRAL (2013, Issue 4). SELECTION CRITERIA: Randomised clinical trials in which LMWH given once daily is compared with LMWH given twice daily for the initial treatment of VTE. DATA COLLECTION AND ANALYSIS: Two review authors assessed trials for inclusion and extracted data independently. MAIN RESULTS: Five studies were included with a total of 1508 participants. The pooled data showed no statistically significant difference in recurrent VTE between the two treatment regimens (OR 0.82, 0.49 to 1.39; P = 0.47). A comparison of major haemorrhagic events (OR 0.77, 0.40 to 1.45; P = 0.41), improvement of thrombus size (OR 1.41, 0.66 to 3.01; P = 0.38) and mortality (OR 1.14, 0.62 to 2.08; P = 0.68) also showed no statistically significant differences between the two treatment regimens. None of the five included studies reported data on post-thrombotic syndrome. AUTHORS' CONCLUSIONS: Once daily treatment with LMWH is as effective and safe as twice daily treatment with LMWH.